JPH1198731A - Motor using rotor with buried permanent magnet therein - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the efficiency of a motor and reduce its vibrations and noises, by so providing, closely to the outer periphery of its rotor core, preventing holes for short circuit of its magnetic fluxes as to contact the preventing holes with the end portions of its permanent-magnet burying holes and its permanent magnets buried therein, and by using its rotor with the permanent magnets buried in the permanent- magnet burying holes. SOLUTION: Making a rotor 2 nearly cylindrical form and making it nearly concentric with a stator 1, it has four magnetic poles oppositely to the inner peripheral surface of the stator 1 to support it rotatably by a bearing through using an shaft 24 as its center. For the rotor 2, there are buried planar permanent magnets 23 in four permanent-magnet burying holes 22 provided at a nearly equal space in the rotational direction of a rotor core 21 and passed through the rotor core 21 in its axial direction. Further, in the rotor 2, closely to the outer periphery of the rotor core 21, preventing holes 27 for the short circuit of magnetic fluxes are so provided that they are contacted with the end portions of the permanent-magnet burying holes 22 and the permanent magnets 23 buried therein to bury the permanent magnets 23 in the permanent-magnet burying holes 22. As a result, a highly efficient motor with low cogging torque and reduced vibrations and noises is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving motor used for an air conditioner or various industrial equipment. In particular, the present invention relates to a structure of a motor in which a permanent magnet is embedded in a rotor core to effectively use not only magnet torque but also reluctance torque.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Patent Application Laid-open No. Hei 8-3
As disclosed in Japanese Patent No. 31823, there is known a motor that achieves high efficiency by embedding permanent magnets in a rotor core and using both magnet torque and reluctance torque. FIG. 15 shows a sectional view of a conventional motor of this type. The stator 1 includes a plurality of teeth 11 and a yoke portion 12 connecting the roots of the teeth 11, and has a substantially annular shape. A plurality of slots 13 formed between the plurality of teeth 11 are provided with three-phase windings. The rotor 7 has a substantially cylindrical shape that is substantially coaxial with the stator 1, has four rotor magnetic poles facing the inner circumferential surface of the stator 1, and has a bearing (not shown) that is rotatable about the shaft 24. Supported by The rotor 7 has plate-shaped permanent magnets 73 buried in four permanent magnet burying holes 72 provided at substantially equal intervals in the rotation direction of the rotor core 71 and penetrating in the axial direction. End plates (not shown) are provided at both ends of the rotor core 71 in the axial direction.
And the rivet pin 26 is passed through the through hole 25 to fix the permanent magnet 73 to the rotor core 71. The outer periphery of the rotor has a notch 77 near the boundary between the rotor magnetic poles, and both ends in the longitudinal direction of the permanent magnet 73 are close to the notch 77. The rotor 7 is rotated by the rotating magnetic field formed by the current flowing through the stator winding, and the rotor magnetic pole is attracted or repelled to the teeth 11 of the stator 1.

In the above configuration, Ld <L is set between inductance Ld in the d-axis direction orthogonal to the rotor magnetic pole and inductance Lq in the q-axis direction passing through the boundary between the rotor magnetic poles.
The relationship of q holds.

Generally, the torque T of a motor is given by T = Pn, where Pn is the number of pole pairs of the rotor, ψa is the flux linkage, I is the stator winding current, and β is the leading phase angle (in electrical angle) of the current I. {a · I · cosβ + 0.5 (Lq−Ld) I ² · sin2β}... (1) In the above equation (1), the first term represents magnet torque, and the second term represents reluctance torque.
Here, when the relationship of Ld <Lq is satisfied, β> 0 is established by performing the current advance control, and reluctance torque is generated. By setting this value of β to a predetermined value,
At the same current, compared to when only magnet torque is used,
It is possible to generate a larger torque T.

[0005]

However, in the above configuration, since the steel plate portion having high magnetic permeability exists between the permanent magnet burying hole and the notch formed in the outer periphery of the rotor, the magnetic flux at the end of the permanent magnet is reduced. However, the short circuit does not effectively contribute to the torque generation across the stator 1 and passes through the magnetic path Pa of the steel plate, that is, the magnet torque is reduced by the short-circuited magnetic flux, and the efficiency is reduced. In addition, due to the generation of the short-circuit magnetic flux, the cogging torque is increased, and vibration and noise are disadvantageously increased.

The present invention has been made to solve the above problems, and provides a motor having high motor efficiency and low vibration and noise.

[0007]

In order to solve the above-mentioned problems, a motor according to the present invention is arranged such that a rotor core is brought into contact with a permanent magnet burying hole and an end of a permanent magnet buried in the hole near an outer periphery of the rotor core. With a magnetic flux short circuit prevention hole
A rotor having the permanent magnet buried in the permanent magnet burying hole is used. This prevents short-circuiting of the magnetic flux at the end of the permanent magnet, and the magnetic flux at the end of the permanent magnet also reaches the stator, effectively acting on torque generation, resulting in high efficiency, low cogging torque, vibration and noise. It provides a small number of motors.

Further, the motor of the present invention comprises
A rotor having a permanent magnet burying hole close to the outer periphery of the rotor core and a magnetic flux short-circuit preventing hole so as to be in contact with an end of the permanent magnet buried therein; and a rotor having the permanent magnet buried in the permanent magnet burying hole. , A substantially annular stator having a plurality of teeth. This prevents short-circuiting of the magnetic flux at both ends of the permanent magnet, and the magnetic flux at the end of the permanent magnet also reaches the stator, effectively acting on torque generation, resulting in high efficiency, low cogging torque, vibration and noise. A small number of motors can be provided.

Preferably, the rotor configuration is such that a permanent magnet burying hole of a certain rotor magnetic pole and a magnetic flux short-circuit preventing hole in contact with an end of the permanent magnet buried therein, and a similar magnetic flux at a rotor magnetic pole adjacent to the rotor magnetic pole When the number of rotor magnetic poles is Nm, the angle θa of the rotor core portion close to the outer circumference of the rotor including the magnetic flux short-circuit prevention hole on the side close to the former magnetic flux short-circuit prevention hole is approximately 120 /.
By setting the degree to Nm, not only the magnetic flux can be effectively used and the efficiency is high, but also the cogging torque and torque pulsation can be reduced, and the vibration and noise can be suppressed low.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A permanent magnet rotor according to the present invention is provided with a permanent magnet burying hole and a magnetic flux short-circuit preventing hole so as to be in contact with an end of a permanent magnet buried in the hole near the outer periphery of a rotor core. The permanent magnet is buried in the permanent magnet burying hole. The short circuit of the magnetic flux at both ends in the circumferential direction of the permanent magnet is prevented, and the magnetic flux of the permanent magnet passes over the stator to effectively work for torque generation, thereby improving the efficiency. And a permanent magnet motor having low cogging torque and low vibration and noise.

Further, the magnetic flux short-circuit preventing hole may be provided inside the outer peripheral end of the rotor core, and a member for forming a rotor core at a narrow interval may be provided between the magnetic flux short-circuit preventing hole and the outer peripheral end of the rotor core. Good.

Further, the angle formed by the width of the portion of the magnetic flux short-circuit preventing hole close to the outer periphery of the rotor core with respect to the center of the rotor core is such that the longitudinal width of the permanent magnet facing the outer periphery of the rotor core is formed with respect to the center of the rotor core. It may be smaller than the angle.

Further, a rotor may be used in which the radial width of the magnetic flux short-circuit preventing hole is at least twice as long as the air gap between the rotor and the stator facing the rotor.

Further, the permanent magnet may be flat. Further, among the holes for preventing magnetic flux short-circuiting which are in contact with the permanent magnet burying hole and the end of the permanent magnet in a certain rotor magnetic pole and the magnetic flux short-circuit preventing hole in the rotor magnetic pole adjacent to the rotor magnetic pole, When the number of rotor poles is Nm, the angle θa of the rotor core portion close to the outer periphery of the rotor including the magnetic flux short-circuit prevention hole on the near side is approximately 120.
/ Nm degrees.

Further, a rotor whose permanent magnet is a rare earth magnet may be used. Further, a non-magnetic material may be arranged on all or a part of the magnetic flux short circuit prevention hole.

Further, the permanent magnet may be molded inside the permanent magnet burying hole and in a space defined by the non-magnetic material.

Further, a rotor having a rotor magnetic pole number Nm of 4 may be used. Further, the ratio of the rotor core outer diameter to the stator core outer diameter may be 0.47 or more and 0.5 or less.

Further, from the end of the magnetic flux short-circuit preventing hole in a certain rotor magnetic pole, the former magnetic flux in the i-th (i is a natural number smaller than the number Nm of rotor magnetic poles) rotor clockwise in the clockwise or counterclockwise direction counted from the rotor magnetic pole. The angle θi to the magnetic flux short circuit prevention hole end corresponding to the short circuit prevention hole end is
The number of teeth of the stator is Nt, j is 0 when the value obtained by dividing the i by Nm / 2, which is half the number of rotor poles Nm, is 0. When the value is not an integer, i between the different i is Nm / j. When the fractional part of the value divided by 2 is the same, it may be less than Nm / 2 and the same integer, and θi = 360 · i / Nm + 720 · j / (Nt · Nm).

Further, the number of stator teeth may be 3 Nm. Further, the width of the portion of the magnetic flux short-circuit prevention hole close to the outer periphery of the rotor core may have two or more values with respect to the center of the rotor core.

Further, a rotor in which a permanent magnet is embedded in an arc-shaped permanent magnet embedding hole that is concave with respect to the outer peripheral side of the rotor may be used.

Further, a plurality of permanent magnet burying holes may be provided in a V-shape with respect to the outer peripheral side of the rotor, and each rotor magnetic pole may be formed by burying a plurality of permanent magnets in the permanent magnet burying holes. .

Further, a permanent magnet may be embedded in the arc-shaped permanent magnet embedding hole concave to the outer peripheral side of the rotor, and separate rotor magnetic poles may be formed inside and outside the arc of the permanent magnet.

[0023] Further, i = l is continuously connected to a rotor magnetic pole adjacent clockwise or counterclockwise with respect to a certain rotor magnetic pole.
, Nm, and the width of a portion of the i-th rotor magnetic pole counted from the reference rotor magnetic pole near the outer periphery of the rotor core in the magnetic flux short circuit prevention hole at the left end of the rotor magnetic pole. Is δ _iL , and δ _{iR at the} right end of the rotor magnetic pole, n is
Is fixed as an integer of 1 or more and Nm / 2 or less, δ _{0L, R} is
0 and less than 60 / Nm degrees, j is the i
Are even and odd numbers, and independently from 0 to (Nm / 2n) -1 at the left and right ends of the rotor magnetic poles.
_{整数 iL, R} =
δ _{0L, R} + 240 · n · j / Nm ² . Further, δ _{0L, R} may be 120 · n / Nm ² . Also, n = 1 may be satisfied. Further, the number of stator teeth may be (3/2) Nm.

[0024]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a sectional view of a motor according to a first embodiment. Stator 1 has 12 teeth 1
1 and a yoke portion 12 connecting the roots of the teeth 11
And has a substantially annular shape. The twelve slots 13 formed between the teeth 11 are subjected to distributed winding of each phase of a three-phase winding at every three pitches.

The rotor 2 has a substantially cylindrical shape substantially coaxial with the stator 1, has four rotor magnetic poles facing the inner peripheral surface of the stator 1, and has a bearing (rotatable about a shaft 24). (Not shown). The rotor 2
Plate-shaped permanent magnets 23 are embedded in four permanent magnet embedding holes 22 which are provided at substantially equal intervals in the rotation direction of the rotor core 21 and penetrate in the axial direction. In addition, the rotor core 21
End plates (not shown) are arranged at both ends in the axial direction of
5 is passed through the rivet pin 26 so that the permanent magnet 2
3 is fixed to the rotor core 21. The rotor 2
The rotor magnetic pole is rotated by being attracted or repelled to the teeth 11 of the stator 1 by a rotating magnetic field formed by a current flowing through a stator winding (not shown).

The rotor 2 is provided with a permanent magnet burying hole 22 near the outer periphery of the rotor core 21 and a magnetic flux short-circuit preventing hole 27 so as to be in contact with the end of the permanent magnet 23 buried therein. The permanent magnet 23 is buried in the permanent magnet burying hole 22.

With such a configuration, the magnetic flux generated from the end of the permanent magnet 23 can be prevented from flowing through the magnetic flux short-circuit preventing hole 2.
7 effectively acts to generate torque over the stator 1 without short-circuiting as in the conventional example of FIG. Thus, a motor with high efficiency, low cogging torque, and low vibration and noise can be realized.

The rotor 2 is provided with a magnetic flux short circuit preventing hole 27.
Is provided inside the outer peripheral end of the rotor core, and a steel plate portion forming the rotor core 21 at a narrow interval is provided between the magnetic flux short-circuit preventing hole 27 and the outer peripheral end of the rotor core.

Here, the distance S between the magnetic flux short-circuit preventing hole 27 and the outer peripheral end of the rotor core is preferably smaller magnetically, but is preferably larger from the viewpoint of strength. Normally, the distance S is preferably equal to or less than the air gap between the rotor 2 and the teeth 11 of the stator 1 and at least 0.8 times the thickness of one laminated steel sheet forming the rotor core 21.

The radial width a of the magnetic flux short-circuit preventing hole 27 should have a sufficiently large value with respect to the air gap between the rotor 2 and the teeth 11 of the stator 1 facing the rotor 2. Desirably, it is usually sufficient to make the air gap twice or more.

The angle formed by the width of the portion of the magnetic flux short circuit preventing hole 27 close to the outer periphery of the rotor core with respect to the center of the rotor core is such that the width of the permanent magnet 23 in the longitudinal direction facing the outer periphery of the rotor core is equal to the center of the rotor core. Smaller than the angle you make.

That is, the length of the portion of the magnetic flux short-circuit preventing hole 27 close to the outer periphery of the rotor core needs to be such that the magnetic flux at the end of the permanent magnet 23 does not hinder the flow of the magnetic flux over the stator 1. By doing so, the permanent magnet 2
The magnetic flux at the three ends reliably contributes to the generation of torque over the stator 1 without short-circuiting at both ends of the end of the permanent magnet 23.

The permanent magnet 23 buried in the permanent magnet burying hole 22 has a flat plate shape, and its manufacture is easy and inexpensive. Further, since the permanent magnet 23 has a flat plate shape, good dimensional accuracy can be ensured, and the gap between the permanent magnet burying hole 22 of the rotor core 21 and the permanent magnet 23 buried therein can be reduced, so that the permanent magnet 23 and the rotor core 21 Since the magnetic resistance between them can be kept small, a motor with high efficiency can be realized.

Further, by using a rare earth magnet as the permanent magnet 23 buried in the permanent magnet burying hole 22, the size of the motor can be reduced. This is because, in a motor having the same output, when a rare earth magnet is used, the magnetic flux density is larger than when a ferrite magnet is used, so that the same efficiency can be realized with about half the volume. Rare-earth magnets have a high coercive force, so their thickness can be reduced.
By reducing the thickness, in the conventional rotor configuration, magnetic flux short-circuits often occur at both ends in the longitudinal direction of the permanent magnet. Therefore, as in the configuration of the present invention, the magnetic flux short-circuit preventing hole 2 is used.
7 is a very effective means to prevent short-circuit of magnetic flux.

With the above configuration, the efficiency is improved by 1 to 3% at each load point as compared with the conventional motor.

In the rotor 2, the number of the permanent magnet burying holes 22 is the same as the number Nm of the rotor magnetic poles. When the radius of the rotor core is r, the thickness b of the end of the permanent magnet 23 is πr /
(3 Nm). In the first embodiment, the number of the permanent magnet burying holes 22 is 4, which is the same as the number of rotor magnetic poles 4. When the radius of the rotor core 21 is r, the thickness b of the end portion of the permanent magnet 23 is πr / What is necessary is just to set it as less than 12.

The rotor 2 has a magnetic flux short-circuit preventing hole 27 in contact with the permanent magnet burying hole 22 and the end of the permanent magnet 23 in a certain rotor magnetic pole, and a magnetic flux short-circuit preventing hole 27 in a rotor magnetic pole adjacent to the rotor magnetic pole. The angle θa of the rotor core portion close to the outer periphery of the rotor including the former magnetic flux short-circuit prevention hole 27 and the magnetic flux short-circuit prevention hole 27.
Are arranged at approximately 120 / Nm degrees. That is, in the first embodiment, since the number of rotor magnetic poles Nm is 4, the angle θa is arranged to be 30 degrees in the rotation direction. Here, it is desirable that the error of the angle θa be less than the distance S between the magnetic flux short circuit preventing hole 27 and the outer periphery of the rotor.

The above reason is as follows. FIG. 5 is a characteristic diagram showing a relationship between the angle θa in FIG. 1 and the cogging torque when the maximum value is set to 1 and normalized. The angle θa is the lowest in the rotation direction at 30 degrees, and is about の of the other angles.

FIG. 6 is a characteristic diagram showing a relationship between the angle θa and a torque pulsation value when a current flows when the maximum value is normalized to 1. 30 degrees is the lowest in the rotation direction, and 35 degrees is the next lowest.

Thus, when the angle θa is 30 degrees,
Both cogging torque and torque pulsation values are the lowest, and are the best in terms of vibration and noise.

It should be noted that a non-magnetic material may be provided on all or a part of the magnetic flux short circuit preventing hole 27. By embedding a non-magnetic material in the magnetic flux short circuit prevention hole 27, the strength of the rotor core 21 is improved.

More specifically, the magnetic flux short-circuit preventing hole 27
For example, by disposing a non-magnetic spacer such as brass or aluminum on all or part of the hole, or by filling and solidifying a non-magnetic fluid, the permanent magnet can be buried in the permanent magnet burial hole by transportation or motor operation. Since there is no vibration inside and the strength is increased, a highly reliable motor can be provided. If aluminum is poured into the entire rotor by aluminum die casting, the end plate and the rivet pin can be integrally formed.

The permanent magnet 23 may be formed inside the permanent magnet burying hole 22 and in a space defined by the non-magnetic material. That is, in a state in which a heat-resistant non-magnetic material such as brass is embedded in the magnetic flux short-circuit preventing hole 27 in advance, a permanent magnet such as a resin magnet is provided in the space defined by the non-magnetic material inside the rotor core 21. If you mold 23,
Since the magnetic pole surface of the permanent magnet 23 is in close contact with the rotor core 21, high reliability can be provided, and a highly efficient motor can be provided because the magnetic resistance is reduced and the amount of magnetic flux is increased. In this case, by providing the non-magnetic material with a taper,
The non-magnetic material may be pulled out of the rotor after the permanent magnet is formed. By doing so, motor loss due to eddy current generated inside the non-magnetic material can be prevented.

FIG. 2 shows a case where the same amount of permanent magnets as the permanent magnet 23 in the first embodiment are used, and the rotor outer diameter and the stator inner diameter are optimally designed in accordance with the number of rotor magnetic poles. FIG. 4 is a characteristic diagram showing a relationship between the number of magnetic poles and a motor loss. As the number of rotor magnetic poles increases, the magnetic flux generated from one magnetic pole of the rotor magnetic pole decreases, and the amount of magnetic flux passing through the teeth portion 11 of the stator 1 decreases accordingly. The amount is reduced. Therefore, the thickness of the yoke part 12 can be reduced.

Therefore, when the outer diameter of the stator is the same, the inner diameter of the stator can be increased and the outer diameter of the rotor can be increased. Since the torque is proportional to the rotor outer diameter, the same torque can be realized with less ampere turns (current × the number of stator windings), and as a result, copper loss is reduced.

That is, the copper loss decreases as the number of rotor poles increases. On the other hand, since the iron loss increases as the frequency increases, the phase switching frequency generally increases as the number of rotor poles increases, and as a result, the iron loss increases.

When the number of rotor magnetic poles is two, if the rotor outer diameter is kept constant and the amount of magnets is the same, the magnetic flux generated from one magnetic pole of the rotor magnetic pole increases, and the teeth 11 of the stator 1 Magnetic saturation occurs in the yoke portion 12 and iron loss increases.

The motor loss is the sum of iron loss and copper loss. As is apparent from FIG.
The smallest pole. Therefore, in the configuration shown in this embodiment, the efficiency is highest when the number of rotor magnetic poles is four.
Further, when the number of rotor magnetic poles is four, if the stator has 12 slots, distributed winding is performed on each phase of the three-phase winding at every three pitches, so that the rotor magnetic flux can be used effectively and the efficiency is high. A motor can be realized.

FIG. 3 shows the relationship between the motor loss and the ratio of the rotor outer diameter to the stator outer diameter when the rotor core 21 is formed by stacking steel sheets having a silicon content of about 3% and a thickness of 0.35 mm. FIG.

FIG. 4 shows the relationship between the motor loss and the ratio of the rotor outer diameter to the stator outer diameter when the rotor core 21 is formed by laminating steel sheets having a silicon content of less than 1% and a thickness of 0.5 mm. FIG.

As is apparent from FIGS. 3 and 4,
As the ratio of the rotor outer diameter to the stator outer diameter increases, copper loss tends to decrease and iron loss tends to increase. In both figures, the motor loss is minimized when the ratio of the rotor outer diameter to the stator outer diameter is between 0.47 and 0.5.
Therefore, the motor efficiency is highest when the ratio of the rotor outer diameter to the stator outer diameter is between 0.47 and 0.5.

(Embodiment 2) FIG. 7 is a sectional view of a motor according to a second embodiment.

From the end of the magnetic flux short-circuit preventing hole at a certain rotor magnetic pole, the former magnetic flux short-circuit preventing at the i-th (i is a natural number less than the rotor magnetic pole number Nm) rotor clockwise or counterclockwise counting from the rotor magnetic pole. The angle θi to the end of the hole for preventing magnetic flux short-circuit corresponding to the end of the hole is as follows:
It is shown by the formula.

Θi = 360 · i / Nm + 720 · j / (Nt · Nm) (2) where Nm is the number of rotor magnetic poles and Nt is the number of teeth of the stator. i is a natural number less than the number Nm of rotor magnetic poles. j indicates that i is half of the number Nm of rotor magnetic poles, that is, N
0 when the value obtained by dividing by m / 2 is an integer, and when the value obtained by dividing i by Nm / 2 is the same, the difference is less than Nm / 2 when the fractional part of the value obtained by dividing i by Nm / 2 is the same. They are the same integer.

In the second embodiment shown in FIG. 7, the number of rotor magnetic poles Nm is 4 poles, and the number of stator teeth Nt is 12 teeth. When each numerical value is applied to the above equation (2), the values of i and j are (Table 1)

[0057]

[Table 1]

The angle θ1 from the end of the magnetic flux short circuit preventing hole 37a to the end of the magnetic flux short circuit preventing hole 37b is i =
By substituting 1, j = 1 into the above equation (2) and calculating, it becomes 105 degrees.

The angle θ2 from the end of the magnetic flux short circuit preventing hole 37a to the end of the magnetic flux short circuit preventing hole 37c is:
Substituting i = 2 and j = 0 into equation (2) yields 180
Degree.

Further, the angle θ3 from the end of the magnetic flux short circuit preventing hole 37a to the end of the magnetic flux short circuit preventing hole 37d.
Is calculated by substituting i = 3 and j = 1 into the equation (2).
85 degrees.

According to the above configuration, there are two magnetic positional relationships between the magnetic poles of the rotor and the teeth of the stator, and the relationship is point-symmetric with respect to the center of the rotor, so that the radial attractive force is made uniform. be able to.

That is, according to the above configuration, when the number of magnetic poles of the rotor is four, there are two magnetic positional relationships between the magnetic poles of the rotor and the teeth of the stator.
Further, although the positional relationship between the teeth that are shifted by approximately 90 degrees and the rotor magnetic poles is different, the positional relationship between the teeth that are shifted by approximately 180 degrees and the rotor magnetic poles is equal. Accordingly, the radially acting force cancels out between the teeth that are displaced by approximately 180 degrees, so that the radially attracting force can be made uniform, so that the cogging torque can be reduced and a motor with less vibration and noise can be provided. it can.

Generally, the cogging torque is determined by the number of rotor magnetic poles Nm and the number of stator teeth Nt per rotation of the rotor.
By the least common multiple Nc. That is, (360 /
There is one change every Nc). Therefore, when the number of teeth Nt of the stator is 3 Nm, there is one variation every (120 / Nm) degrees. However, by setting the positional relationship between the tip of the magnetic flux short-circuit prevention hole and the tip of the teeth of the stator in two ways as in the second embodiment, (60 / Nm)
Each time, the fluctuation is one, and the fluctuation of the cogging torque can be 6 Nm per rotation.

In FIG. 5, the magnetic flux of the former one of the magnetic flux short-circuit preventing hole in contact with the permanent magnet burying hole and the end of the permanent magnet in one rotor magnetic pole and the magnetic flux short-circuit preventing hole in the rotor magnetic pole adjacent to the rotor magnetic pole is shown. The angle θa of the rotor core portion close to the outer periphery of the rotor including the magnetic flux short-circuit prevention hole on the side close to the short-circuit prevention hole is 3 degrees in the same rotation direction.
Even at 0 degrees, the cogging torque is lower in the case of unequal pitch as in the second embodiment shown in FIG. 7 than in the case of equal pitch as in the first embodiment shown in FIG. The period of the waveform is also doubled. That is, while the cogging torque of the first embodiment fluctuates 12 times per rotation, the second
It will fluctuate 24 times, with the cogging torque being smoothed and lower.

In FIG. 6, even when the angle θa is 30 degrees in the same rotational direction, the angle θa is smaller than that of the first embodiment shown in FIG. The torque pulsation is lower in the case of unequal pitch as in the embodiment.

Therefore, the motor according to the second embodiment is low in both cogging torque and torque pulsation value, and is superior to the first embodiment in terms of vibration and noise.

(Embodiment 3) FIG. 8 is a sectional view of a motor according to a third embodiment.

The permanent magnet burying hole 42 of the rotor core 41 has a concave arc shape on the outer peripheral side of the rotor, and a plate-like permanent magnet 43 is buried in the hole 42.

With the above configuration, the surface area of the permanent magnet 43 can be made larger than that of the first embodiment shown in FIG.
Large torque can be obtained. At this time, the permanent magnet 4
If the radius of the rotor 3 is equal to or smaller than the radius of the rotor, the surface area of the permanent magnet 43 is preferably larger than the surface area of one pole of the rotor. When the holding force of the permanent magnet 43 to be used is relatively low, the required magnetic flux amount can be secured by this configuration, which is effective.

(Embodiment 4) FIG. 9 is a sectional view of a motor according to a fourth embodiment.

A plurality of permanent magnet burying holes are provided in a V-shape with respect to the outer peripheral side of the rotor, and a plurality of permanent magnets are buried in the permanent magnet burying holes.

More specifically, two permanent magnets 53a and 53b having a flat plate shape are embedded in each of the holes 52 for embedding the permanent magnets in the rotor core 51. Since the permanent magnets 53a and 53b are plate-shaped, the manufacture of the magnets is easy and inexpensive. The permanent magnet 53a
Since the and 53b are plate-shaped, good dimensional accuracy can be ensured, and the gap between them and the permanent magnet burying hole 52 can be reduced. Therefore, the permanent magnets 53a and 53b
Since the magnetic resistance between the motor and the rotor core 51 can be reduced, a highly efficient motor can be provided. Also, the permanent magnet 53
As in the third embodiment shown in FIG. 8, the surface area of a and 53b can be made larger than in the first embodiment shown in FIG. 1, and a large torque can be obtained.

(Embodiment 5) FIG. 10 is a sectional view of a motor according to a fifth embodiment.

The rotor 6 has a permanent magnet 63 embedded in an arc-shaped permanent magnet embedding hole 62 that is concave with respect to the rotor outer peripheral side, and separate rotor magnetic poles are formed inside and outside the arc of the permanent magnet 63. I have. Since one rotor magnetic pole is formed inside the arc of the permanent magnet 63 and the other rotor magnetic pole is formed outside the arc, the number of permanent magnets may be half the number of rotor magnetic poles,
This is particularly advantageous when an expensive rare earth magnet is used for the permanent magnet 63.

In this case, when the number of the permanent magnet burying holes 62 is Nm / 2, which is half of the number Nm of the rotor magnetic poles, and the radius of the rotor core 61 is r, the thickness b of the end portion of the permanent magnet 63 is It may be less than πr / (3Nm).

A magnetic flux short-circuit preventing hole 67 is provided near the outer periphery of the rotor core 61 so as to be in contact with the permanent magnet burying hole 62 and the end of the permanent magnet 63 buried therein. Buried hole 62 for permanent magnet including 67
The angle θa of the portion close to the outer periphery of the rotor is 30 degrees in the rotation direction.

In this case, the angle θa is determined by the magnetic flux short-circuit preventing hole 67 in contact with the permanent magnet embedding hole 62 and the end of the permanent magnet 63 in a certain rotor magnetic pole and the magnetic flux short-circuit preventing hole in the rotor magnetic pole adjacent to the rotor magnetic pole. This is an example in which there is no magnetic flux short-circuit prevention hole close to the former magnetic flux short-circuit prevention hole, and the angle θa of the present invention includes the above case.

The operation of the magnetic flux short-circuit preventing hole 67 is the same as that of the first embodiment, and will not be described.

In FIG. 10, the magnetic flux short-circuit preventing holes 67 extend on one side of each end of the permanent magnet 63. However, as shown in FIG. The magnetic flux short-circuit prevention holes 68 and 69 may be extended. In this case, the flow of the magnetic flux is more uniform than that of FIG. 10, which is preferable.

(Embodiment 6) FIG. 12 is a sectional view of a motor according to a sixth embodiment.

The stator 80 is composed of twelve teeth 81 and a yoke portion 82 connecting the roots of the teeth 81 and has a substantially annular shape.
The two slots 83 are provided with windings 84 formed by concentrated winding of the teeth 81. The rotor 8 includes a stator 8
It has a substantially cylindrical shape substantially coaxial with 0, has eight rotor magnetic poles facing the inner circumferential surface of the stator, and is supported by a bearing (not shown) so as to be rotatable about a shaft 94. I have. The rotor 8 has plate-shaped permanent magnets 93 embedded in eight permanent magnet embedding holes 92 which are provided at substantially equal intervals in the rotation direction of the rotor core 91 and penetrate in the axial direction. Also,
End plates (not shown) are arranged at both ends of the rotor core 91 in the axial direction, and the permanent magnets 93 are fixed to the rotor core 91 by passing rivet pins 96 through through holes 95. The rotor 8 is rotated by attracting or repelling a rotor magnetic pole to a rotating magnetic field formed by a current flowing through the stator winding 84. Permanent magnet burial hole 9
2 have a magnetic flux short-circuit preventing hole 97 near the outer periphery of the rotor, and a permanent magnet burying hole 92 and a magnetic flux short-circuit preventing hole 97 in contact with the end of the permanent magnet 93 at a certain rotor magnetic pole. Of the magnetic flux short-circuit preventing hole 97 in the rotor magnetic pole adjacent to the rotor magnetic pole, and the magnetic flux short-circuit preventing hole 97 on the side closer to the former magnetic flux short-circuit preventing hole 97. Is about 120 / Nm, that is, about 15 degrees.

Continuously to a rotor magnetic pole adjacent in a clockwise or counterclockwise direction with respect to a certain rotor magnetic pole, i = 1, 2,
.., Nm, and the width of the portion of the i-th rotor magnetic pole counted from the reference rotor magnetic pole near the outer periphery of the rotor core of the magnetic flux short-circuit prevention hole at the left end of the rotor magnetic pole is set at the center of the rotor core. Assuming that the angle to be formed is δ _iL and that of the right end of the rotor magnetic pole is δ _iR , the δ _iL and δ _iR are expressed by the following equations (3).

Δ _{iL, R} = δ _{0L, R} + 240 · n · j / Nm ² (3) where Nm is the number of rotor magnetic poles. n is 1 or more, N
j is an integer from 0 to (Nm / 2n) -1 independently when i is an even number and an odd number, and independently at the left and right ends of the rotor magnetic pole. Are taken n times each.

Δ _{0L, R} is larger than 0 and 60 / N
m degrees and is as in the following equation (4).

Δ _{0L, R} = 120 · n / Nm ² (4) Here, for example, when n = 1 and Nm = 8, only one of the possible values of j is taken as an example. The values of δ _iL are shown in (Table 2).

[0086]

[Table 2]

The value of δ _iR is automatically determined as shown in (Table 3) in order to make the width of approximately 120 / Nm = 15 degrees by combining the adjacent magnetic flux short prevention holes.

[0088]

[Table 3]

Although the calculated values are shown in the above (Table 2) and (Table 3), in FIG. 12, the values are rounded off to the second decimal place for convenience of angle accuracy.

When the number of teeth of the stator is (3/2) Nm, the positional relationship between the magnetic poles of the rotor and the tips of the teeth of the stator is (120 / Nm) between the odd-numbered rotor magnetic poles and the even-numbered rotor magnetic poles. And the cogging torque fluctuates 3 Nm times per rotation of the rotor. Further, the angle of the magnetic flux short-circuit preventing hole of each of the odd-numbered rotor magnetic poles and the even-numbered rotor magnetic poles is expressed by Nm / 2 according to the above equation.
As a result, the cogging torque fluctuates (3/2) Nm ² times per one rotation of the rotor, and the fluctuation cycle of the cogging torque can be reduced. Therefore, the value of the cogging torque can be reduced. A motor with low noise can be provided.

When processing is difficult due to the dimensions and processing accuracy of the rotor core 91, as shown in FIG.
1, but the effect of reducing vibration and noise is smaller than that of the motor shown in FIG. When n = 2, only one of the possible values of j is taken as an example, and δ _iL , δ _iR
Are shown in (Table 4).

[0092]

[Table 4]

Although the calculated values are shown in the above (Table 4), FIG. 13 shows the values rounded off to the second decimal place for convenience of angle accuracy.

FIG. 14 shows the characteristics of the motor without the magnetic flux short-circuit preventing hole, the motor of FIG. 12, and the motor of FIG. 13 at the same input, torque pulsation at the time of energization, and cogging torque at the time of non-energization. FIG. Each value was standardized as 1 for a motor without a magnetic flux short circuit prevention hole. As is clear from FIG. 14, in the motor shown in this embodiment,
Without dropping torque, torque pulsation is 20-30%,
The cogging torque could be reduced by 70 to 80%.
Also, by increasing the frequency of the excitation force, vibration and sound insulation can be easily performed.

As for the angle defined in the above description, an error within a range of about 5% is allowable in terms of characteristics.

In the present invention, the permanent magnet embedded in the rotor may be formed by molding a solid magnet into the permanent magnet embedding hole or by molding a molded magnet such as a resin magnet into the permanent magnet embedding hole. It goes without saying that it may be formed.

Although the present invention has been described in connection with the various embodiments described above, it is to be understood that various other modifications may be made.

The embodiments used in the specification and the drawings do not limit the present invention. Further, the details of the present embodiment do not limit the scope of the claims.

[0099]

According to the first aspect of the present invention, the short circuit of the magnetic flux at both ends of the permanent magnet is prevented, the magnetic flux of the permanent magnet reaches the stator and works effectively to generate torque, thereby improving the efficiency and Provided is a permanent magnet motor having low cogging torque and low vibration and noise.

According to the fourth aspect of the present invention, the magnetic flux at the end of the permanent magnet reliably contributes to the generation of torque over the stator 1 without short-circuiting at both ends.

According to the sixth aspect of the present invention, since the permanent magnet is inexpensive and has good dimensional accuracy, the gap between the rotor core and the permanent magnet can be reduced, and a highly efficient permanent magnet motor is provided.

According to the seventh aspect of the present invention, the number of permanent magnets can be reduced, and short-circuit of magnetic flux at both ends of the permanent magnet can be prevented.
Provided is a permanent magnet motor in which the efficiency is increased, the cogging torque is low, and the vibration and noise are low, by the magnetic flux of the permanent magnet being effectively transmitted to the stator to generate torque.

According to the eighth aspect of the invention, since the rare earth magnet has a high coercive force, its thickness can be reduced, and the size and efficiency of the permanent magnet can be reduced.

According to the ninth aspect of the present invention, the strength of the rotor is increased without the permanent magnet vibrating inside the permanent magnet burying hole of the rotor core, and a highly reliable permanent magnet motor is provided.

According to the tenth aspect of the present invention, the magnetic pole surface of the permanent magnet is in close contact with the rotor core, so that a permanent magnet motor having low magnetic resistance and high efficiency is provided.

According to the eleventh aspect of the present invention, there is provided a highly efficient permanent magnet motor in which iron loss and copper loss are balanced.

According to the twelfth aspect of the present invention, there is provided a highly efficient permanent magnet motor in which iron loss and copper loss are balanced.

According to the thirteenth aspect, the suction force in the radial direction can be made uniform, so that the cogging torque can be reduced and a motor with less vibration and noise can be provided.

According to the nineteenth aspect of the present invention, there is provided a permanent magnet motor capable of reducing cogging torque and reducing vibration and noise.

According to the twentieth aspect of the present invention, there is provided a permanent magnet motor capable of reducing cogging torque and reducing vibration and noise.

According to the twenty-first aspect of the present invention, there is provided a permanent magnet motor having high efficiency and low vibration and noise.

[Brief description of the drawings]

FIG. 1 is a sectional view of a motor showing a first embodiment of the present invention.

FIG. 2 is a characteristic diagram showing the relationship between the number of rotor poles and motor loss when the same amount of permanent magnets are used and the rotor outer diameter and the stator inner diameter are optimally designed according to the number of rotor poles.

FIG. 3 is a characteristic diagram showing a relationship between a motor loss and a ratio of a rotor outer diameter to a stator outer diameter when a steel sheet having a large silicon content is used for a rotor core.

FIG. 4 is a characteristic diagram showing a relationship between a motor loss and a ratio of a rotor outer diameter to a stator outer diameter when a steel sheet having a small silicon content is used for a rotor core.

FIG. 5 is a characteristic diagram showing a relationship between an angle θa and a cogging torque in a rotor core.

FIG. 6 is a characteristic diagram showing a relationship between an angle θa and a torque pulsation value in a rotor core.

FIG. 7 is a sectional view of a motor showing a second embodiment of the present invention.

FIG. 8 is a sectional view of a motor according to a third embodiment of the present invention.

FIG. 9 is a sectional view of a motor showing a fourth embodiment of the present invention.

FIG. 10 is a sectional view of a motor according to a fifth embodiment of the present invention.

FIG. 11 is a sectional view of another motor according to a fifth embodiment of the present invention.

FIG. 12 is a sectional view of a motor showing a sixth embodiment of the present invention.

FIG. 13 is a sectional view of another motor according to the sixth embodiment of the present invention.

FIG. 14 is a characteristic diagram showing a relationship between motor specifications and torque, torque pulsation value, and cogging torque.

FIG. 15 is a sectional view of a conventional motor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Stator 2 Rotor 11 Teeth 21 Rotor core 22 Permanent magnet embedding hole 23 Permanent magnet 27 Permanent magnet short circuit prevention hole

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI H02K 21/16 H02K 21/16 M (72) Inventor Takeshi Morishige 1006 Odakadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72 ) Inventor Kazuhiro Ohara 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture (72) Inside the Matsushita Electric Industrial Co., Ltd. 1006 Kadoma, Matsushita Electric Industrial Co., Ltd. (72) Inventor Naoyuki Kadoya 1006 Kadoma Kadoma, Kadoma City, Osaka Pref. Matsushita Electric Industrial Co., Ltd. Inside the corporation

Claims (22)

[Claims] 1. A permanent magnet burying hole and a magnetic flux short-circuit preventing hole are provided in contact with an end of a permanent magnet buried in the permanent magnet burying hole. Rotor with embedded magnet. 2. A permanent magnet burying hole is provided in the vicinity of the outer periphery of the rotor core, and a magnetic flux short-circuit preventing hole is provided so as to be in contact with an end of the permanent magnet buried therein. A motor having a rotor having a magnet embedded therein and a substantially annular stator having a plurality of teeth. 3. A magnetic flux short-circuit prevention hole portion is provided inside the outer peripheral end of the rotor core, and a member portion for forming a rotor core at a narrow interval is provided between the magnetic flux short-circuit prevention hole portion and the rotor core outer peripheral end. Item 7. The rotor according to Item 1. 4. The angle formed by the width of the portion of the hole for preventing short-circuit of the magnetic flux close to the outer periphery of the rotor core with respect to the center of the rotor core is such that the longitudinal width of the permanent magnet facing the outer periphery of the rotor core is formed with respect to the center of the rotor core. 2. The rotor according to claim 1, wherein the angle is smaller than the angle. 5. The radial width of the magnetic flux short-circuit preventing hole is:
3. The motor according to claim 1, wherein the rotor has a length at least twice as long as an air gap between the rotor and a stator facing the rotor. 6. The rotor according to claim 1, wherein the permanent magnet has a plate shape. 7. A magnetic flux short-circuit preventing hole which contacts a permanent magnet embedding hole and a permanent magnet end of a certain rotor magnetic pole, and a magnetic flux short-circuit preventing hole of a rotor magnetic pole adjacent to the rotor magnetic pole. When the number of rotor magnetic poles is Nm, the angle θa of the rotor core portion close to the outer periphery of the rotor including the magnetic flux short-circuit preventing hole on the side closer to the rotor hole is approximately 12
2. The rotor according to claim 1, wherein the rotor is disposed at 0 / Nm degrees. 8. The rotor according to claim 1, wherein a rotor whose permanent magnet is a rare earth magnet is used. 9. The rotor according to claim 1, wherein a non-magnetic material is provided in all or a part of the magnetic flux short-circuit preventing hole. 10. The rotor according to claim 9, wherein a permanent magnet is formed inside the permanent magnet burying hole and in a space defined by the nonmagnetic material. 11. The rotor according to claim 1, wherein a rotor having a rotor magnetic pole number Nm of 4 is used. 12. The motor according to claim 2, wherein the ratio of the outer diameter of the rotor core to the outer diameter of the stator core is 0.47 or more and 0.5 or less. 13. The former magnetic flux at the i-th (i is a natural number less than Nm of the number of rotor magnetic poles) rotor clockwise or counterclockwise counting from the rotor magnetic poles from the end of the magnetic flux short-circuit preventing hole at a certain rotor magnetic pole. The angle θi to the magnetic flux short-circuit prevention hole end corresponding to the short-circuit prevention hole end is obtained by dividing the number of teeth of the stator by Nt and j, and dividing the i by Nm / 2 which is half of the number Nm of rotor magnetic poles. 0 when it is an integer, and i
When the fractional part of the value obtained by dividing by Nm / 2 is the same, when it is smaller than Nm / 2 and the same integer, θi = 360 · i / Nm + 720 · j / (Nt · Nm). 2. The motor according to 2. 14. The motor according to claim 2, wherein the number of stator teeth is 3 Nm. 15. The motor according to claim 1, wherein the angle formed by the width of the portion of the magnetic flux short-circuit prevention hole close to the outer periphery of the rotor core has two or more values with respect to the center of the rotor core. 16. The rotor according to claim 1, wherein a permanent magnet is embedded in an arc-shaped permanent magnet embedding hole that is concave with respect to the outer peripheral side of the rotor. 17. The rotor magnetic pole according to claim 1, wherein a plurality of permanent magnet burying holes are provided in a V-shape with respect to the outer peripheral side of the rotor, and the plurality of permanent magnets are buried in the permanent magnet burying holes. The rotor as described. 18. The rotor according to claim 1, wherein a permanent magnet is buried in an arc-shaped permanent magnet burying hole that is concave with respect to the outer peripheral side of the rotor, and separate rotor magnetic poles are formed inside and outside the arc of the permanent magnet. . 19. Continuously to a rotor pole adjacent clockwise or counterclockwise with respect to a certain rotor pole, i = 1,
2,..., Nm, and the width of a portion of the i-th rotor magnetic pole counted from the reference rotor magnetic pole near the outer periphery of the rotor core of the magnetic flux short-circuit prevention hole at the left end of the rotor magnetic pole is the rotor core. When the angle to the center is δ _iL and that at the right end of the rotor magnetic pole is δ _iR , n is
Is fixed as an integer of 1 or more and Nm / 2 or less, δ _{0L, R} is
0 and less than 60 / Nm degrees, j is the i
Are even and odd numbers, and independently from 0 to (Nm / 2n) -1 at the left and right ends of the rotor magnetic poles.
The motor according to claim 1 or 2, wherein each of the integers up to n is taken n times, and _{δiL, R} = _{δ0L, R +} 240 · n · j / Nm ² . 20. The motor according to claim 19 _{, wherein} δ _{0L, R} = 120 · n / Nm ² . 21. The motor according to claim 19, wherein n = 1. 22. The number of stator teeth is (3/2) Nm
3. The motor according to claim 2, wherein